1. Field of the Invention
The present invention relates to an air filter, especially to an air filter for filtering suspended particles from air.
2. Description of the Prior Arts
An air filter is a device for filtering suspended particles from air, and is usually installed in a ventilation system of a building, an air compressor, or an engine of a vehicle. The conventional air filter such as an air cleaner disclosed in U.S. Pat. No. 6,190,432 as shown in FIG. 8 comprises a housing 91, a filter core 92 and a sealing system 93. The housing 91 has a first housing 911 and a second housing 912. The first and second housings 911, 912 are assembled together, and an accommodating space is formed between the first and second housings 911, 912. The first housing 911 has an outlet 914 communicating with the accommodating space. The second housing 912 has an inlet 913 communicating with the accommodating space.
With reference to FIGS. 8 to 10, the filter core 92 is mounted in the accommodating space and has a wavy filtering sheet 922 and a flat filtering sheet 921, both for filtering suspended pollutants. The wavy filtering sheet 922 and the flat filtering sheet 921 are rolled into a cylinder and are alternately stacked to form multiple layers of the wavy filtering sheet 922 and layers of the flat filtering sheet 921. Thus, two surfaces of each layer of the wavy filtering sheet 922 are respectively flush with two adjacent layers of the flat filtering sheet 921. Multiple channels 923A, 923B are formed between each layer of the wavy filtering sheet 922 and the two adjacent layers of the flat filtering sheet 921A, 921B. An end sealing adhesive layer 924A is adhered between each layer of the wavy filtering sheet 922 at the side adjacent to the inlet 913 and one of the layers of the flat filtering sheet 921A that are adjacent to said layer of wavy filtering sheet 922. Thus, the channels 923A between said layer of the wavy filtering sheet 922 and said layer of the flat filtering sheet 921A are sealed at the side adjacent to the inlet 913. Another end sealing adhesive layer 924B is adhered between said layer of the wavy filtering sheet 922 at the side adjacent to the outlet 914 and the other layer of the flat filtering sheet 921B that is adjacent to said layer of the wavy filtering sheet 922. Thus, the channels 923B between said layer of the wavy filtering sheet 922 and said layer of the flat filtering sheet 921B are sealed at the side adjacent to the outlet 914. As a result, the air to be filtered enters the cylinder-rolled filter core 92 from the inlet 913 of the second housing 912, and then enters channels 923B, which are not sealed at the side adjacent to the inlet 913. Afterwards, the air axially moves to the other end of the channels 923B, and is unable to flow out from the filter core 92 due to the end sealing adhesive layer 924B. Thus, the air would pass through the layer of the wavy filtering sheet 922 to arrive at another channels 923A, such that the air can flow out from the filter core 92 to arrive at the outlet 914. When the air passes through the layer of the wavy filtering sheet 922, the wavy filtering sheet 922 filters the suspended particles from the air to clean the air. In addition, the air may pass through the layer of the flat filtering sheet 921B to arrive at another channel, and said layer of the flat filtering sheet 921B also can filter the suspended particles from the air.
With reference to FIG. 8, the sealing system 93 has an annular frame 931 and a seal member 932. The annular frame 931 is mounted around the filter core 92 in an end adjacent to the outlet 914. The seal member 932 is mounted around the annular frame 931 in an end adjacent to the outlet 914, and transversely abuts an inner wall of the first housing 911. The seal member 932 is made of pressable and resilient material, and an original outer diameter of the seal member 932 is bigger than an inner diameter of the first housing 911 at a position corresponding to the seal member 932. The seal member 932 is pressed transversely to transversely and tightly abut the inner wall of the first housing 911, thereby transversely sealing a gap between the filter core 92 and the first housing 911. Accordingly, the air to be filtered must pass through the filter core 92 to arrive at the outlet 914.
However, the conventional air filter has the following shortcomings.
First, the sealing system 93 seals the gap between the filter core 92 and the first housing 911 by transversely compressing the seal member 923, and thus the outer diameter of the seal member 923 is bigger than the inner diameter of the corresponding position of the first housing 911 as mentioned above. Accordingly, installing the sealing system 93 into the first housing 911 is difficult, since the user has to apply much physical force to push the sealing system 93 into the first housing 911.
Second, with reference to FIGS. 9 and 10, the conventional wavy filtering sheet 922 and the flat filtering sheet 921 are adhered to each other by adhesives 925. The adhesives 925 are spread on a surface of the flat filtering sheet 921 and extended along an elongated side of the flat filtering sheet 921. Since the wavy filtering sheet 922 undulates as a wave, the flat filtering sheet 921 only adheres to a small part of peaks of the wavy filtering sheet 922, and thus the adhered area between the flat filtering sheet 921 and the wavy filtering sheet 922 are too small to securely connect the filtering sheets 921, 922 to each other. Besides, the adhesives 925 are spread between any two peaks, and thus occupy a part of the space of the channels 923A, 923B, thereby interfering with the flowing of the air. In addition, since the adhesives 925 are spread on only one surface of the flat filtering sheet 921, each layer of the wavy filtering sheet 922 is only adhered to one of the layers of the flat filtering sheet 921B, and is not adhered to the other layer of the flat filtering sheet 921B. As a result, the connection between the flat filtering sheet 921 and the wavy filtering sheet 922 is not strong enough. After in use for a period of time, the wavy filtering sheet 922 and the flat filtering sheet 921 may have stained with suspended particles, which lower the filtering efficiency. Therefore, to clean the wavy filtering sheet 922 and the flat filtering sheet 921, clean air is blown into the filtering core from the outlet 914. When the clean air passes through the wavy filtering sheet 922 and the flat filtering sheet 921 in a reverse direction, the air brings the stained suspended particles out of the filtering sheets 921, 922, and the air is blown out of the inlet 913 together with the suspended particles. However, the connection between the flat filtering sheet 921 and the wavy filtering sheet 922 is not strong enough, and there is no annular frame 931 in an end adjacent to the inlet 913 to axially abut the filter core 92. Consequently, as the air blows, the layers of the wavy filtering sheet 922 and the flat filtering sheet 921 in the center of the filter core 92 may separate from each other and axially protrude out along the blowing direction of the air, which causes the filter core 92 to be dysfunctional.
Third, with reference to FIG. 8, as mentioned above, the annular frame 931 axially abuts and fixes the filter core 92. The annular frame 931 has multiple connecting ribs 9311. The connecting ribs 9311 are transversely connected to an inner wall of the annular frames 931, and axially abut the filter core 92. However, the connecting ribs 9311 also block the channels of the filter core 92 at the abutment position of the connecting ribs 9311, and thus the air flow is interfered.
To overcome the shortcomings, the present invention provides an air filter to mitigate or obviate the aforementioned problems.